1. Technical Field
The present invention relates to a developing device that is provided to an image forming apparatus such as laser printer.
2. Background
In an image forming apparatus, it is known a related printer including a process cartridge, which has a drum cartridge holding a photosensitive drum and a developing cartridge holding a developing roller and removably mounted to the drum cartridge, is removably mounted.
As the developing cartridge mounted to the printer, a developing cartridge has been provided to which a lower frame holding a developing roller and an upper frame assembled to the lower frame are welded.
In the developing cartridge, the upper frame has a main body part having a plate shape and a beam-shaped part mounted to a front end of the main body part, and a welding rib to be welded to upper surfaces of a left sidewall, a right sidewall and a rear sidewall of the lower frame is formed at a periphery of a lower surface of the main body part. In other words, the welding rib is continuously formed on the lower surfaces of left, right and rear end portions of the main body part, and the welding rib has a substantial U shape having an opened front side.
When welding the upper and lower frames, a second seal member, which is to be squashed by front end portions of the welding rib, is sandwiched between the beam-shaped part of the upper frame and the left-and-right sidewalls of the lower frame, and then a second seal member is welded together with the front end portions of the welding rib.
In addition, when the upper frame and the lower frame are welded to each other, a front side end of the beam-shaped part of the upper frame is substantially flush with front end of the left-and-right sidewalls of the lower frame.
A first seal member is adhered to straddle over both the front side end of the beam-shaped part of the upper frame and the front end of the left-and-right sidewalls of the lower frame.
The second seal member suppresses toner leakage from between the beam-shaped part of the upper frame and the left-and-right sidewalls of the lower frame. The first seal member suppresses toner leakage from between the front side end of the beam-shaped part of the upper frame and the front face of the left-and-right sidewalls of the lower frame.